2017 American Samoa




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A greeneye fish turns its attention towards the Deep Discoverer. We saw several of these fishes during the dive.

A greeneye fish turns its attention towards the Deep Discoverer. We saw several of these fishes during the dive. Click image for credit and larger view.

video Watch video of an amphipod seen during the dive.

 


NOAA Ship Okeanos Explorer
February 28, 2017

Dive 13: Nautilus Site

Today's dive marked the end of 2017 American Samoa Expedition: Suesuega o le Moana o Amerika Samoa. We explored an area near the harbor of Pago Pago, American Samoa, at a site where a population of Nautili (cephalopod mollusks with a chambered shell) has been observed using baited cameras in the Taema Bank area. We dove to a depth of ~460 meters and ascended to 250 meters over the course of the dive. While we did not see any nautili during the dive, but we encountered several species of bottomfishes and corals. We also saw some unfamiliar fauna at mesophotic and sub-mesophotic zones, including potential new species of anemone, brisingid sea star, and octocorals. We ended the dive with a vertical transect to the edge of the wall and an ascent through the twilight water column.


 


 

 

 

This Bolosoma stalked glass sponge may represent a new species.

This Bolosoma stalked glass sponge may represent a new species. Click image for credit and larger view.

video Watch video of the sponge.

 


NOAA Ship Okeanos Explorer
February 27, 2017

Dive 12: Malulu Seamount

The twelfth dive of the expedition took place on Malulu Seamount, beginning near the summit at a depth of ~2,500 meters and moving up. Prior to reaching the summit, the substrate was mostly ferromanganese cobble welded to the seafloor, consistent with being either a volcaniclastic deposit or a talus deposit that has been covered with ferromanganese. During the dive, scientists were able to characterize dense sponge and coral habits on the slope and top of the seamount. Corals observed included Pleurogorgia and Chrysogorgia colonies, as well as bamboo whip and Bathypathes black corals. We saw several stalked sponges (Bolosoma and Callophacus) and we collected what may be a new species of Bolosoma. Many observed dead sponge stalks had ophiuroid brittle star associates. Brisingid seastars were common. We also observed and collected a goniasterid cookie star that is likely new species. Near the summiting ridge, we saw more abundant sediment with ripples, while the ridge top and right side exhibited very little sediment; based on these observations, scientists were able to identify the direction of predominant currents on the top portions of the seamount. The dive ended with exploration of the mid-water column, characterizing animals that live between 1,500 and 375 meters depth.


 


 

 

 

View from Seirios as remotely operated vehicle Deep Discoverer gets a closer look at a ferromanganese-encrusted outcrop.

View from Seirios as remotely operated vehicle Deep Discoverer gets a closer look at a ferromanganese-encrusted outcrop. Click image for credit and larger view.

Close-up look at a holothurian sea cucumber reveals digestive tract full of sediment.

Close-up look at a holothurian sea cucumber reveals digestive tract full of sediment. Click image for credit and larger view.

video Watch video about sampling collection during the dive.

 


NOAA Ship Okeanos Explorer
February 26, 2017

Dive 11: "Seamount D"

During Dive 11, we explored "Seamount D," which lies in the eastern region of the Samoan Exclusive Economic Zone (EEZ). Seamounts located this far east in the Samoan EEZ had not been sampled prior to this expedition. Bathymetry collected during the expedition revealed the seamount to have a conical shape with a prominent ridge extending to the northwest. The dive began at a depth of ~3,000 meters, similar to depths reached during Dive 06 to explore on Utu Seamount, providing interesting comparison between the dives, as there were evident similarities in the benthic communities on both seamounts. Like at Utu Seamount, on Seamount D, we observed several species of octocorals, including chrysogorgiids (including Pleurogorgia and Iridogorgia), isidid bamboo corals, and whip and branching primnoids. We also saw numerous stalked and non-stalked sponges on large outcrops. Throughout most of the dive, the seafloor was composed of ferromanganese boulders and cobbles, with large outcrops, often with steep walls and overhangs. Geochemical analysis of rock samples collected during the dive can help to test the hypothesis that this seamount is an ancient volcano that formed by a different, non-Samoan hotspot.


 


 

 

 

Scorpionfish resting on the seafloor at 343m in the Rose Atoll Marine National Monument.

Scorpionfish resting on the seafloor at 343 meters in Rose Atoll Marine National Monument. Click image for credit and larger view.

video Watch video of an octopus and a hermit crab seen during the dive.

 


NOAA Ship Okeanos Explorer
February 25, 2017

Dive 10: Rose Atoll

During today's dive, we explored a prominent ridge extending from the eastern region of Rose Atoll; the deeper portions of the ridge were explored during Dive 03 of the expedition. We started at a depth of ~ 700 meters and moved upslope to a depth of ~ 250 meters. For much of the dive, the seafloor was ferromanganese material that looks like basalt flows or pillow structures; however, it is also possible that the substrate is ferromanganese carbonate from a submerged reef. A range of animals were observed along this bottom, including living and dead sponges, urchins, cup corals, a mushroom coral (Anthomastus), a dandelion siphonophore, a pycnogonid sea spider, scorpion fish, deepwater cardinal fish, and eels. As Deep Discoverer moved upslope, we eventually encountered substrate dominated by smooth carbonate surfaces; dissolution of the carbonate resulted in complex and elaborate "sculptures," including nearly "hollowed out" boulders, pinnacles, and overhanging ledges. Frequently encountered animals included bamboo corals, soft octocorals and chrysogorgiid-like octocorals, small black coral colonies (Parantipathes sp?), scleractinian corals, cup corals, anemones, crinoids, and sponges. A range of fish were observed during the dive, including commercially important bottomfish such as grouper (Hypothodus octofasciatus), yellow snapper, and a school of large Etelis snapper fish.

Information from this dive will help us to better understand the diversity and structure of deep biological communities, including bottomfish and precious corals habitats, with the goal of supporting management needs of Rose Atoll Marine National Monument. Rose Atoll lies in the eastern region of the Samoan islands. Following the hotspot model, the eastern Samoan islands are predicted to be the youngest volcanic islands; however, Rose Atoll has features that suggests it is in fact quite old, calling into question Rose Atoll's relationship with the Samoan hotspot. Indeed, existing work shows that the geochemistry of dredged lavas from the deep flanks of Rose Atoll are not consistent with an origin at the Samoan hotspot. Geochemical analysis of geologic samples collected during the dive will help to discern the age and origin of Rose Atoll.


 


 

 

 

Young pillow basalts on Vailulu'u, with an age of perhaps five year or less.

Young pillow basalts on Vailulu'u, with an age of perhaps five year or less. Click image for credit and larger view.

While we did not see many fish during the dive, we did catch a glimpse of a thresher shark as it circled near Seirios, above ROV Deep Discoverer.

While we did not see many fish during the dive, we did catch a glimpse of a thresher shark as it circled near Seirios, above ROV Deep Discoverer. Click image for credit and larger view.

video Watch video of a ctenophore imaged during the dive or an overall summary of the dive.

 


NOAA Ship Okeanos Explorer
February 24, 2017

Dive 09: Vailulu'u Seamount

During Dive 09 of the expedition, we explored Vailulu'u seamount, an active volcano lying in the eastern region of the Samoan hotspot. Comparison of multibeam data collected in 2012 with new bathymetric data collected during this expedition show that the volcanic cone in the crater, called Nafanua, has grown substantially since the seamount was last mapped in 2012, having formed two distinct volcanic features. The new mapping data also showed plumes (likely composed of carbon dioxide gas) rising from the location of previously identified hydrothermal vents.

Today's dive started at a depth of ~900 meters, within the crater of Vailulu'u and approximately 50 meters east of the hydrothermal activity. However, upon reaching the seafloor near the hydrothermal vent field, the water was so turbid that visibility was severely limited and we had to move to a different location with better visibility. This extreme turbidity is a change from the last visual remotely operated vehicle (ROV) observation of the seamount, which occurred in 2005.

In exploring the youngest volcanic feature on Nafauna, we consistently observed spectacular pillow basalts as the ROV moved along the bottom, some (likely older) pillows partially covered with sediment. However, all lavas on Nafanua are less than 18 years of age, as Nafanua did not exist in the crater when mapped in 1999. Carnivorous sponges, anemones, ophiuroid brittle stars, and stalked hydroids were seen on some of the pillows. Upon reaching the second new volcanic feature on Nafauna, we saw a significant change in the morphology of the flows. Instead of the classical pillow basalt structures observed earlier, the flows were chaotic "broken" structures; it is not clear what is responsible for this change in lava morphology. On the summit of Nafanua, where flows are known to be older, rock surfaces had an orange-brown color, suggesting significant hydrothermal alteration. Fresher (grey) surfaces were juxtaposed with the orange-brown surfaces, suggesting a recent disturbance, possibly a landslide. Here, we observed several Anthomatus corals, larger carnivorous sponges and anemones, and hydroids. The large degree of sediment cover, in addition to the greater degree of biological diversity and the larger size of the fauna, is consistent with a lack of recent growth on the summit of Nafanua.


 


 

 

 

 Close up of a monoplacophoran mollusk, which may be the animal responsible with the trails of ‘clean’ rock observed throughout the dive.

Close up of a monoplacophoran mollusk, which may be the animal responsible with the trails of 'clean' rock observed throughout the dive. Click image for credit and larger view.

video Watch video of holothurian (sea cucumber) seen during the dive.

 


NOAA Ship Okeanos Explorer
February 23, 2017

Dive 08: Return to "Utu" Seamount

Today's dive took us back to "Utu" seamount. Located in the northern region of the American Samoa Exclusive Economic Zone, the seamount appears to be composed of two distinct structures – a pancake-shaped structure at the base and a steeper-sided volcanic structure on top. After exploring the crater wall of the shallower volcanic structure during Dive 06, today we explored the deep flanks of the seamount, starting at approximately 4,000 meters depth and targeting the blocky base upon which the shallower, younger volcanic structure is built. Geologic samples collected during the dive will help to define the age and origin of the seamount and its relationship to  hotspots in the region. Over the course of the dive, we saw a range of bottom types, including relatively flat, ferromanganese-encrusted surfaces; ferromanganese cobbles and pebbles; and pillow structures encrusted with ferromanganese deposits. Potbelly and stalked (Caulophacus) sponges were seen often, as were small ophiuroids. We collected two dead sponge stalks, both with crinoid and anemone associates. A truly exciting find during the dive was the observation of what appeared to be a monoplacophoran mollusk. This "living fossil" is mostly known from surveys of soft bottom abyssal plains and this represented the first time the organism was seen alive by any of the scientists participating in the dive. Attempts to collect a specimen were, unfortunately, unsuccessful.


 


 

 

 

Yellow zoanthids colonizing the base of a dead golden octocoral skeleton. Several living colonies of golden octocorals in the background.

Yellow zoanthids colonizing the base of a dead golden octocoral skeleton. Several living colonies of golden octocorals in the background. Click image for credit and larger view.

video Watch video of a flytrap anemone seen during the dive.

 


NOAA Ship Okeanos Explorer
February 22, 2017

Dive 07: "Moki" Seamount

The seamount exploredon this dive, tentatively called "Moki" seamount, lies on the northern region of the American Samoa Exclusive Economic Zone. Upon reaching the seafloor at a depth of ~2,200 meters, the remotely operated vehicle (ROV) encountered ferromanganese outcrops covered with many chrysogorgiid octocorals (Pleurogorgia), some with brittle star, zoanthid, anemone, and hydroid associates. Intermixed with the live octocorals were also dead corals colonized by zoanthids and worms. We then moved through a series of steep walls constructed of pillow basalts lightly covered with sediment, before reaching a talus field of ferromanganese cobbles. Along the way, we observed any abundance of corals (whip black corals, Iridogorgia, Chrysogorgia, Pleurogorgia, and isidid colonies) as well as squat lobsters, anemones, hydroids, brisingid sea stars, and ophiuroids. During the dive, only one fish, a halosaur, and one glass sponge were seen.


 


 

 

 

A chrysogorgiid octocoral seen with an ophiuroid brittle star associate on bare coral skeleton, which is very unusual as brittle stars are usually associated with healthy coral tissue.

A chrysogorgiid octocoral seen with an ophiuroid brittle star associate on bare coral skeleton, which is very unusual as brittle stars are usually associated with healthy coral tissue. Click image for credit and larger view.

video Watch video of a "cosmic" jellyfish from the dive.

 


NOAA Ship Okeanos Explorer
February 21, 2017

Dive 06: "Utu" Seamount

A previously unexplored seamount, tentatively called "Utu," was the target for Dive 06 of the expedition. Located in the northern region of the American Samoa Exclusive Economic Zone, the seamount appears to be composed of two distinct structures – a pancake-shaped structure at the base and a steeper-sided volcanic structure on top – which are consistent with two stages of volcanic activity on the seamount. The summit of the seamount is host to a clearly developed volcanic crater. During the dive, we explored along the crater wall of the shallower volcanic structure, starting at a depth of ~ 3,040 meters.

For the initial part of the dive, the bottom was predominantly sediment, as well as loose pebbles, cobbles, and boulders; few animals were observed. As the remotely operated vehicle moved closer to the crater wall, the landscape became increasingly dominated by large blocks and boulders (all ferromanganese encrusted), with light-colored sediment infilling the spaces between the blocks and cobbles. The loose rock, which is likely from volcanic material that had broken off the crater wall and rolled down hill, hosted a wide range of animals. Corals observed during the dive included numerous chrysogorgiid octocorals, whip and branching primnoids, and Iridogorgia. Moving along the dive track, we also observed glass sponges, sea stars, carnivorous tunicates, crinoids, and anemones, as well as several halosaurs and two cusk eels. Near the summit of the crater wall, the dive ended in spectacular fashion, with large outcrops and a large abundance of stalked glass sponges (Bolosoma) over a meter tall, several large octocoral fans (likely bamboos or primnoids), Iridogorgia, and large bamboo whips over 1.5 meters tall.


 


 

 

 

A brisingid sea star clings to a ferromanganese cobble. The cobble, and the associated sea star, were collected shortly after being imaged by D2.

A brisingid sea star clings to a ferromanganese cobble. The cobble, and the associated sea star, were collected shortly after being imaged by D2. Click image for credit and larger view.

video Watch video of a solitary hydroid seen during the dive.

 


NOAA Ship Okeanos Explorer
February 20, 2017

Dive 05: "Leoso" Seamount

During today's dive, we explored a seamount tentatively called "Leoso" seamount, which straddles the boundary between the American Samoa Exclusive Economic Zone (EEZ) and the Cook Islands EEZ. The seamount appears to be comprised of two distinct structures: a larger, flat-topped guyot at the base topped by a smaller, flat-topped volcanic structure that is consistent with being a rejuvenated (or post-erosional) stage of volcanism for the seamount. The dive started at a depth of ~3,770 meters, midway up a steep portion of the smaller, shallower volcanic structure. Deep Discoverer (D2) landed on a ferromanganese-encrusted surface, possibly a lava flow, partially covered with some loose cobbles. As D2 moved upslope, the terrain transitioned first from an increasing percentage of cobble cover, to being dominated by flow structures, and then to smooth, ferromanganese-encrusted pillow basalts. Throughout the dive, we encountered several glass sponges, including many stalked (Bolosoma) and non-stalked sponges, both dead and alive. We also observed black animal tracks on some rocks, possibly made by holothurians or snails. Other animals seen included small ophiuroid brittle stars, hydroids, asymmetric yellow urchins (possibly Pilematechinus; one was collected), barnacles, anemones, and a likely new species of cookie sea star. Only one coral was observed during the dive – the black coral Bathypathes, for which a sample was collected. The dive ended on the top of the seamount, where we observed a smooth surface of ferromanganese crust covered with a thin, rippled layer of sediment and very little to no fauna.


 


 

 

 

Today's dive was cancelled due to increasingly heavy winds and seas. Here, ROV Deep Discoverer is recovered and safely brought back on deck.

Today's dive was cancelled due to increasingly heavy winds and seas. Here, ROV Deep Discoverer is recovered and safely brought back on deck. Click image for credit and larger view.

 


NOAA Ship Okeanos Explorer
February 19, 2017

Dive 04: Cancelled Due to Weather

Following overnight mapping operations, the science team woke up very early today to evaluate newly collected mapping data and select a dive site on an unexplored seamount located about 20 nautical miles south of the southeast corner of Rose Atoll Marine National Monument. Shortly after deployment of the remotely operated vehicle (ROV) for Dive 04, the weather picked up and continued building, with wind gusts over 35 knots. We cancelled the dive and recovered the ROV. The onboard team spent the afternoon catching up on paperwork, developing outreach materials, and continuing to evaluate the weather to determine contingency plans for the coming days.


 


 

 

 

Ferromanganese nodules fill the field of view. The center of each nodule may host a basaltic rock, sediment, or even a fossil.

Ferromanganese nodules fill the field of view. The center of each nodule may host a basaltic rock, sediment, or even a fossil. Click image for credit and larger view.

video Watch video of a beautiful dandelion siphophore.

 


NOAA Ship Okeanos Explorer
February 18, 2017

Dive 03: Rose Atoll

The dive began at 2,538 meters on a large ridge extending away from the east side of Rose Atoll and moved north to the ridge crest, revealing abundant individual ferromanganese nodules with no noticeable sessile (attached) fauna. The narrow spaces between nodules were filled with light-colored, sandy-textured sediment – possibly carbonate from the reef. A ferromanganese-encrusted rock was collected while a sea cucumber swam in the distance. Moving uphill, Deep Discoverer (D2) observed several ophiuroid brittle stars, two different kinds of crinoids, a dandelion siphonophore, two types of sea cucumbers, a possibly new species of sea star, carnivorous and other glass sponges, corals, and several large, old manganese-encrusted sponge skeletons. When D2 arrived on top of what appeared to be a ferromanganese-encrusted lava flow, the geology changed to more boulders. A final geologic sample, roughly twice the size of the first boulder, was collected. Continuing along the dive track, the abundance and diversity of corals increased. As the terrain varied with rougher flow textures, which may have been talus deposits cemented with ferromanganese deposits, there were beautiful pillow structures. The current increased and the slope became steeper; it was entirely composed of pillow basalts that gave way to sparsely sedimented ropy lava textures. The benthic community remained relatively constant – bamboos, chrysogorgiids with associates, and black corals. Around 2,415 meters, several dead sponge stalks and a large branching bamboo colony with a predatory sea star were observed. The topography became highly varied, containing five to 10-meter vertical walls. A large block of pillow flows, which appeared unattached to the flows below, was observed and may have been the result of a large landslide. The flow edge terminated and boulders with large quantities of sediment dominated the area; many overhanging ledges had large dislodged blocks of basalt. Loose boulders, reduced abundance of animals, and manganese-encrusted sponge skeletons were seen at about 2,360 meters. The top of one of these sponges containing other sponges, barnacles and hydroids was collected. We will continue seamount sampling on our next dive!


 


 

 

 

A deepwater longtail red snapper (Etelis coruscans) measuring one meter (three feet) long, observed at 353 meters depth on a southeastern ridge off Ta’u island, within National Marine Sanctuary of American Samoa.

A deepwater longtail red snapper (Etelis coruscans) measuring one meter (three feet) long, observed at 353 meters depth on a southeastern ridge off Ta'u island, within National Marine Sanctuary of American Samoa. Click image for credit and larger view.

video Watch video of a searobin seen during the dive walking across the seafloor.

 


NOAA Ship Okeanos Explorer
February 17, 2017

Dive 02: Ta'u Unit of National Marine Sanctuary of American Samoa

The dive began at a depth of around 500 meters on the ridge extending away from the southwest side of Ta'u, a relatively flat area consisting of basalt rock lightly dusted with a light-colored sediment, and ended within the bounds of the Ta'u Unit of National Marine Sanctuary of American Samoa. Several striped squat lobsters, large-clawed hermit crabs with zoanthid symbionts, cup corals, robin fish, large-eyed shrimp, red/purple urchins, chrysogorgiid coral, a snake eel, and a toad fish were all observed in this area. Moving northward along the top of the ridge were larger basalt boulders, many sponges, ophiuroid brittle stars (including a species with stripped arms and red oral disk with white dots), different fish species, sea stars, corals, and crinoids. As Deep Discoverer (D2) continued along the dive track, the bottom composition appeared to vary; at different points it appeared to be carbonate, then clay, and later volcanic sediment welded together possibly with a chemical precipitate "cement." At the top of the ridge, a peculiar folded-fan shape primnoid octocoral was collected; it had associated snapping shrimp and a tiny yellow squat lobster. A pencil urchin, potentially feeding on spider crab, as well as a fourth kind of crinoid were also seen in this area. Numerous crevices in the rocks had ophiuroids living in them. Great abundance of red/purple echinothuriid urchins were seen as well – it was an echinoderm wonderland! Cardinal fishes hid in the cracks and D2 observed noticeably fewer suspension feeders than at shallower depths. Around 350 meters, animal abundance increased, with plentiful soft corals, yellow crinoids, and several half- living stony corals. During collection of a mushroom octocoral, we observed shimmering water from thermocline fluctuations (plus or minus 1°C). Commercially important bottomfish, including snapper and several seabass, were first observed in shallower water. When we got to the top of a flat terrace, we observed a new kind of stalked crinoid as well as many "fried egg" anemones. There was an incredible abundance of dead skeletons, potentially black corals, overgrown by what seemed to be hydrozoans. At the end of the dive, we sampled a basaltic rock as we observed numerous anemones and mushroom corals.


 


 

 

 

NOAA Ship Okeanos Explorer docked at the pier at the Port of Pago Pago in American Samoa. Significant outreach was conducted prior to commencing the expedition. Interviews were conducted with media, and ship tours were held for local elementary through college students, local partners, government and agency representatives.
NOAA Ship Okeanos Explorer docked at the pier at the Port of Pago Pago in American Samoa. Significant outreach was conducted prior to commencing the expedition. Interviews were conducted with media, and ship tours were held for local elementary through college students, local partners, government and agency representatives.

NOAA Ship Okeanos Explorer docked at the pier at the Port of Pago Pago in American Samoa. Significant outreach was conducted prior to commencing the expedition. Interviews were conducted with media, and ship tours were held for local elementary through college students, local partners, and government and agency representatives. Click image for credit and larger view.

 


NOAA Ship Okeanos Explorer
February 16, 2017

Underway!

NOAA Ship Okeanos Explorer departed Pago Pago harbor this morning to commence the first cruise leg of the 2017 American Samoa Expedition! Our first dive was conducted just outside the harbor at a site with a known Nautilus community. However, shortly before the remotely operated vehicle (ROV) reached the bottom, a mechanical issue occurred and the ROV had to be immediately recovered. The ROV engineering team expects to fix the problem tonight. After recovery, mapping operations will be conducted overtop of a ridge extending southeast of Tutuila island on the way to our next dive site at Ta'u.


 


 

 

 

 

 

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